1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly, to an image forming apparatus that is equipped with an improved developer detecting device and agitating device mounted to a developer storage part.
2. Description of the Related Art
Generally, an image forming apparatus is an apparatus that prints an image on a printing medium, e.g., paper, according to an input image signal. As one example of the image forming apparatus, an electrophotographic image forming apparatus is configured such that a light beam is scanned onto a photosensitive member charged with an electric potential to form an electrostatic latent image thereon, and then the electrostatic latent image is developed to a visible image by adhering a developer onto the electrostatic latent image, and the visible image is then transferred and fixed onto paper.
In such a printing process, a developer contained in a developing device of an image forming apparatus is regularly consumed. If the developer is totally consumed, a user replaces the developing device itself or a developer cartridge in the developing device. So as to enable the user to replace the developing device or the developer cartridge at the right time, the developing device is typically provided with a developer detecting device for detecting an amount of developer remaining. Japanese Patent Laid-open Publication No. 2004-61971 discloses one example of a conventional image forming apparatus with a developer detecting device.
The conventional image forming apparatus includes a light emitting part, a light receiving part, and two optical fibers which guide light emitted from the light emitting part to the light receiving part. The light emitting part and the light receiving part are mounted in a main body of the image forming apparatus, and the optical fibers are mounted in a developing device. One optical fiber is connected to the light emitting part, the other optical fiber is connected to the light receiving part, and a developer detecting part for detecting an amount of developer is interposed between the two optical fibers. If the light emitted from the light emitting part is blocked by the developer filled in the developer detecting part and cannot be transmitted to the light receiving part, it is determined that sufficient developer remains. On the other hand, if the light emitted from the light emitting part is transmitted to the light receiving part through the developer detecting part and the optical fibers, it is determined that the developer is almost exhausted.
The above conventional image forming apparatus can prevent a decrease of light intensity in the developing device by using the optical fibers. However, because the optical fiber is expensive, it is not economical.
Also, the developing device is typically provided with an agitating device for agitating the developer therein. However, the conventional image forming apparatus has difficulty in arranging optical fibers and optical fiber supporting members without interference with the agitating device.
The visible image developed on the photosensitive member is transferred to the paper directly or via an intermediate transfer device. When the visible image is transferred to the paper or to the intermediate transfer device from the photosensitive member, or when the visible image is transferred to the paper from the intermediate transfer device, the image is not totally transferred, but instead a portion of the developer remains on the photosensitive member or the intermediate transfer device. The residual waste developer is collected by a waste developer collecting device, and is stored in a waste developer container.
If the waste developer container is filled with the waste developer, the user replaces the waste developer container. Similarly to the developing device, so as to enable the user to replace the waste developer container at the right time, the waste developer container is typically provided with a waste developer detecting device.
Korean Patent Laid-open Publication No. 2006-0037955 discloses a device for detecting an amount of waste developer stored in a waste developer container. The conventional waste developer detecting device includes a light emitting part and a light receiving part disposed opposite to the light emitting part. When the light receiving part cannot receive the light from the light emitting part, it is determined that the waste developer is stored in the waste developer container above a predetermined amount.
However, the conventional image forming apparatus equipped with the above conventional waste developer detecting device alerts a user to replace the waste developer container just before the waste developer container is full of waste developer. Therefore, unless the user prepares a new waste developer container in advance, the user cannot use the image forming apparatus until preparing a new waste developer container.
Considering the above problem, a plurality of light emitting parts positioned at different heights and a plurality of light receiving parts corresponding to the respective light emitting parts may be provided, so as to inform the user of the amount of waste developer stored in the waste developer container by stages. However, it causes an increase in manufacturing costs due to the increased number of the light emitting parts and the light receiving parts.